Mechanized Process For Improved Removal Of Elements Such As Labels From An Adhesive Film During Manufacture

ABSTRACT

A manufacturing process that allows for the transfer of labels formed from a film to end-use products. The film is covered by a masking layer that is typically die cut to create the labels from the continuous sheet of film. Here, an additional covering layer (or layers) of a relatively stiff material is disposed over the masking layer. The addition of the covering layer results in the processed film being less susceptible to damage (related to unwanted bending) during further processing and/or shipment. Advantageously, the covering layer improves the ability to remove individual labels from the film, particularly with respect to attempting to peel off the thin masking layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/578,771, filed Jan. 19, 2022, which is a divisional of U.S. PatentApplication 16/591,680, filed Oct. 3, 2019 and wherein both applicationsare incorporated by reference.

TECHNICAL FIELD

The present invention relates to a simplified process for separating outindividual labels from a film used to support the labels in amanufacturing process, allowing for the transfer of labels from the filmto end-use products.

BACKGROUND OF THE INVENTION

Invisible indicia printed with an optically active material on asubstrate can be used as a covert security feature on products andproduct packaging. The product is then authenticated by revealing theinvisible indicia with the use of an appropriate source of polarizedlight or a polarized filter.

To select a suitable anti-counterfeit technology, it needs to be notonly easy to be recognized but also difficult to be copied, so that theselected anti-counterfeit technology can truly provide the desiredprotection. One such technology utilizes a polarizer film (linear orcircular) to create indicia that is only revealed when viewed withpolarized light (and thus otherwise “invisible” to the naked eye).

In the field of linear polarizers, some improvements inanti-counterfeiting have been associated with the use multiple layers ofpolarizing film, each oriented at a different polarization, such that agiven “stack” of multiple films will exhibit a more complicatedpolarization pattern. However, the cost and complexity of such amultilayer process is considered to be a disincentive to widespread use.

SUMMARY OF THE INVENTION

The needs remaining in the art are addressed by the present invention,which relates to polarizer films and, more particularly, to a multi-axispolarizer film created using a printing process of multiple sets of axesat different spatial locations on a single layer of film.

Instead of “stretching” a film to create polarization axes as in theprior art, a printing plate (patterned to include several sets ofgrooves at various orientations; a “multi-axis” pattern) is used totransfer the multi-axis groove pattern to a plastic film. The patternstake the form of shallow grooves embossed in the film. The grooved filmis then saturated with an appropriate polarizing liquid dye material(e.g., iodine or any other suitable dichroic liquid dye). The dyemolecules align with the multi-axis grooves in the film, and thus createa polarizer with a multi-axis pattern, defined only by the printedgroove pattern. This is in contrast to prior art arrangements where thepolarizer film was limited to a two-axis form defined by the stretchdirection of the film itself.

In addition to the creation of a multi-axis polarization film, thepresent invention provides an improved manufacturing process that allowsfor the transfer of labels formed from this polarizer film to end-useproducts.

Other and further aspects and embodiments of the present invention willbecome apparent during the course of the following discussion and byreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, where like numerals represent like partsin several views:

FIG. 1 is a diagram illustrating the prior art technique of stretchingthe film to create defined lines for polarization of the film;

FIG. 2 is a simplified diagram of a multi-axis polarizer film formed inaccordance with the present invention;

FIG. 3 illustrates an exemplary printing plate used to create multiplepatterns of spatially-separated lines across the surface of a film;

FIG. 4 is a diagram depicting an exemplary process of transferring thepattern from the printing plate of FIG. 3 to a section of film;

FIG. 5 illustrates the application of a dichroic dye to the printed filmof FIG. 4 , creating sets of polarized lines at different spatiallocations across the film;

FIG. 6 shows a subsequent step in the formation of individual polarizeddevices, including cutting through the polarized film, with a thinprotective masking layer used to protect the surface of the polarizerfilm;

FIG. 7 shows a step of applying a stiff, protective covering to the cutfilm; and

FIG. 8 shows a step of removing the stiff, protective covering (as wellas an underlying protective thin masking layer) in the formation ofindividual devices.

DETAILED DESCRIPTION

Most film-based polarized sheets are made by a stretching process thatapplies a tension to the film so as to create an “absorbing axis” thatruns parallel to the stretch direction, with the “transmitting axis”thus running perpendicular to the stretch direction. FIG. 1 illustratesthis prior art principle, showing a section of stretched film 1 (forexample, a film of polyvinyl-alcohol (PVA)) with an absorbing axis A inthe direction shown. A suitable liquid polarizing dye material (forexample, iodine), is applied to the stretched film. The iodine moleculesalign along the absorbing axis A of the PVA film and thus create thepolarizing effect. Such a film is typically defined as a “linear”polarizer, since the dye molecules will be disposed in lines along theabsorbing axis. It is clear that the axes are defined by the stretchingprocess and that a given sheet of film is limited to exhibit only a2-axis polarization configuration (i.e., an absorbing axis and atransmitting axis).

Instead of using a stretching process, a multi-axis polarizer film isformed in accordance with the present invention by using a printingprocess to create a plurality of sets of “grooves” at various, differentlocations across the surface of the film. As described in detail below,a printing plate may be used in one process of introducing the sets ofgrooves to a standard film, where the printing plate is formed toinclude a number of grooves (in the form of sets of parallel grooves indifferent spatial locations organized in any desired pattern, includinga random pattern). The printing plate then transfers the grooves to aplastic film (such as PVA, or cellulose triacetate (CTA), or any otherplastic film material used for this purpose) in a simple printing(embossing) process. A rotogravure printing process (or other suitableprocess) is then used to apply a liquid polarizing dye material (e.g.,iodine or other suitable dichroic liquid dye) to the printed film. Thedye molecules will thus align along the various grooves formed in thefilm, forming a multi-axis polarizer film in accordance with the presentinvention, where the specific “groove pattern” in the film defines theorientations of the multi-axis polarizer. Indeed, a significant aspectof the present invention is that a specific, unique set of grooves maybe associated with a particular product, vendor, or the like, providingyet another level of source authenticity.

FIG. 2 illustrates an exemplary multi-axis polarizer film 10 formed inaccordance with the present invention. In this exemplary embodiment, aset of three different groove patterns 12, 14, and 16 are shown asformed at different spatial locations in film 10. Each pattern is shownas comprising several parallel grooves. These patterns are exemplaryonly; a significant advantage of the printing technique of the presentinvention is the ability to form grooves along various axial directionsat different locations along film 10. Each pattern is shown asexhibiting a different angle of orientation with respect to what wouldbe the “stretch” (absorbing) axis in a prior art film. The ability toreplicate such a multi-axis pattern using the conventional stretchprocess is considered to be essentially impossible; thus, the use of themulti-axis polarizer film of the present invention as an authenticationlabel is considered to be a preferred alternative.

FIGS. 3-5 illustrate an exemplary set of steps that may be used to forma multi-axis polarizer film in accordance with the principles of thepresent invention.

FIG. 3 shows a printing plate 20 that is formed to include a pluralityof grooves 22 formed in a plate top surface 24. Grooves 22 comprise setsof parallel lines and may be formed by etching grooves using knownphotolithographic processes, mechanical processes, or the like. In onecase, printing plate 20 may be formed of an aluminum plate. Grooves 22are shown as formed in different orientations at different locationsacross the surface of printing plate 20. For example, it is possible toexpose different sections of plate 20 at different times, thus providingthe ability to create grooves running in different directions in anyrandom pattern. The use of a spatial distribution of different sets ofparallel grooves thus allows for the formation of a “multi-axis”polarization film in accordance with the principles of the presentinvention.

FIG. 4 illustrates the next step in the process, where printing plate 20is then pressed into film 10 to transfer the groove pattern to film 10.Thus, referring back to FIG. 2 , the printing process is used to creategroove patterns such as 12, 14, and 16 across a section of film 10. Asthe film continues to move with respect to plate 20, the pattern iscontinuously transferred to subsequent sections of film 10. At times,this is referred to as an embossing process or a printing process.

Lastly, a polarizing liquid dye material 30 is applied to the embossedfilm, as shown in FIG. 5 (the term “applied” is considered to includedprocesses where the film is placed in a liquid bath of dye material 30).As described above, the dye molecules in liquid 30 will align along eachset of groove patterns (such as 12, 14, and 16) forming a separate“polarizer” section along the axis of each groove pattern, creating a“multi-axis” polarizer film. A rotogavure process is one exemplaryprocess that may be used for transferring the polarizing liquid to thefilm, where a rotating printing plate is engaged with a moving film tocontinuously “print” the pattern into newly-presented sections of thefilm.

Once the multi-axis polarizer is created on a film, an adhesive isapplied to the film and then the film is cut into the individualelements. A coating of clear or reflective material may be applied tothe multi-axis polarizer film prior to applying the adhesive. Typically,laser or die cutting is used to define the outline of the individualelements. A protective layer of masking material is preferably used toprotect the “raw” surface of the polarizer film during the cuttingprocedure. The masking layer may be applied to only one side of thepolarizer film, or both sides of the film. The masking layer istypically thin, and needs to be easily “peelable” once the individualdevices have been formed. Depending on the size of the individualdevices, it may be difficult (or tedious) to peel away the small size,thin masking material.

Another aspect of the present invention relates to a simplified processfor later separating out individual elements (e.g., labels used forproducts as an anti-counterfeiting device) from a polarizer film.Indeed, while a significant use may be anti-counterfeiting devicelabels, the technique for quickly and repeatedly removing labels from anoriginal film with little or no waste is a significant advance in and ofitself.

FIG. 6 is a side view of an exemplary polarizer film 100 with aprotective masking layer 40, where a laser cutting operation has beenperformed (indicated by the vertical dashed lines) to create a pluralityof individual devices 100-1, 100-2, . . . , 100-N, each device stillincluding its portion of overlying protective masking layer 40. It is tobe understood that a second protective masking layer 40′ may be placedacross the bottom surface of film 100; for the sake of clarity, thedrawings shown only a masking layer on the top-side of film 100. Oncemasking layer(s) 40 is(are) in place, film 100 may also be cut into longstrips, each strip retaining its portion of protective masking layer(s)40, with some type of frame-tab structure used to keep the individualdevices 100-1 through 100-N from being fully removed from film 100.

In accordance with the present invention, instead of attempting toremove layer 40 from the individual devices 100-i, a covering layer 50is disposed over and attached to protective masking layer 40 subsequentto the laser cutting step. This is shown in FIG. 7 , which again onlyshows a covering layer 50 over the “top” side of film 10; it is to beunderstood that if an additional masking layer 40′ is disposed acrossthe bottom surface of film 10, an additional covering layer 50′ may bepositioned over masking layer 40′. In accordance with the process of thepresent invention, covering layer(s) 50 is(are) perhaps stiffer thanprotective masking layer 40, and may also be thicker, although this isnot a requirement. A benefit of covering layer 50 is that the furtherprocessing and shipment of processed polarizer film 10 will be lesssusceptible to damage from bending.

Once it is desired to place individual devices 100-i on end-use productsor labeling, the user peels off one or both of layers 50 (as the casemay be), which takes protecting covering layer(s) 40 along during theremoval process, as shown in FIG. 8 . The user can thus simply removeindividual devices 100-1 through 100-N from the strip.

Various modifications and alterations of this invention will be apparentto those skilled in the art without departing from the spirit and scopeof the invention. Indeed, it should be understood that this invention isnot limited to the illustrative embodiments set forth herein and isinstead contemplated as being limited only by the scope of the claimsappended hereto.

What is claimed is:
 1. A method of making labels, comprising the stepsof: a) providing a sheet of film formed to include a label pattern; b)applying a masking layer over an exposed major surface of the film; c)cutting through a portion of the thickness of the structure of step b)at predetermined locations defined as boundaries for individual labelelements, retaining a web frame portion of the masking layer; d)applying a covering layer over the cut surface of the masking layer soas to adhere to each cut portion of the masking layer; and e) pullingthe covering layer away from the major surface of the sheet of film,wherein the act of pulling the covering layer also removes theunderlying, adhered cut portions of the masking layer.
 2. The method asdefined in claim 1 wherein steps b) through d) are repeated on aremaining, opposing major surface of the film, with step e) used to pullthe covering layer away from both major surfaces of the polarizer film.3. The method as defined in claim 1, wherein step a) is further definedas providing a polarizer film.
 4. The method as defined in claim 1wherein step d) is performed multiple times to form multiple coveringlayers the over the masking layer, a subsequent covering layer adheringto a top surface of a previously applied covering layer.
 5. The methodas defined in claim 4 wherein step d) is performed until the combinationof multiple covering layers is thicker than the previously appliedmasking layer.
 6. The method as defined in claim 1 wherein the coveringlayer comprises a material thicker than that of the masking layer.